B\to K_1\pi(K) decays in the perturbative QCD approach

TL;DR

This paper investigates B to K_1 pi(K) decays using perturbative QCD, highlighting discrepancies with experimental data, exploring annihilation decay channels, and analyzing CP asymmetries related to mixing angles.

Contribution

It provides new predictions for decay channels and CP asymmetries within the perturbative QCD framework, especially for annihilation-dominated processes.

Findings

Certain decay modes are incompatible with experimental data.

Pure annihilation decays have predicted branching ratios around 10^{-7}.

CP asymmetries depend on the mixing angle θ_{K_1}.

Abstract

Within the framework of the perturbative QCD approach, we study the two-body charmless decays $B\to K_1(1270)(K_1(1400))\pi(K)$. We find the following results: (i) The decays $\bar B^0\to K_1(1270)^+\pi^-, K_1(1400)^+\pi^-$ are incompatible with the present experimental data. There exists a similar situation for the decays $\bar B^0\to a_1(1260)^+K^-, b_1(1235)^+K^-$, which are usually considered that the nonperturbative contributions are needed to explain the data. But the difference is that the nonperturbative contributions seem to play opposite roles in these two groups of decays.(ii) The pure annihilation type decays $\bar B^0\to K_1^{\pm}(1270)K^{\mp}, K_1^{\pm}(1400)K^{\mp}$ are good channels to test whether an approach can be used to calculate correctly the strength of the penguin-annihilation amplitudes. Their branching ratios are predicted at $10^{-7}$ order, which are larger than the QCDF results. (iii) The dependence of the direct CP-violating asymmetries of these decays on the mixing angle $\theta_{K_1}$ are also considered.